1. Technical Field
This invention relates to device for insufflating gas into a mass of molten metal.
2. Description of the Prior Art
Prior structures of this type have generally employed frusto-conical permeable plugs positioned in frusto-conical cavities in pocket blocks in the refractory lining of the ladle. Typical devices may be seen in U.S. Pats. Nos. 3,834,685, 4,053,147 and 4,462,576. The LaBate prior art U.S. Pat. Nos. 4,396,179, 4,481,809, 4,483,520 and 4,538,795 disclose non-permeable refractory plugs of frusto-conical shape provided with metal jackets and positioned in frusto-conical cavities in pocket blocks. The LaBate pending application Ser. No. 06/769,143 illustrates a solid non-permeable refractory plug of frusto-conical shape with a spaced metal jacket positioned in a frusto-conical shaped cavity in a pocket block with the upper end of the plug and the jacket extending above the upper surface of the pocket block to form a hot metal dam.
The present invention substantially improves the stirring efficiency of gas introduced into molten metal and the metallurgical reactions that are responsive thereto due to the substantially increased area of the annular column of gas flowing upwardly through the molten metal which is achieved by the inverted frusto-conical shape of the solid plug, the metal shell thereon and the inverted frusto-conical shape of the cavity in the pocket block which very substantially enlarges the area of the device through which the gas enters the molten metal.